function raymig(figno,pts)
% RAYMIG: raytrace migrate a picked event assuming normal incidence
%
% raymig(figno,pts)
%
% RAYMIG uses a velocity model initialized by RAYVELMOD and a
% vector of points picked using PLOTIMAGE. For each pair of points,
% a normal incidence ray is determined and projected down into the
% velocity model.
%
% figno ... figure number to plot the rays in
% pts ... n x 2 matrix of (x,t) vaues from PLOTIMAGE or equivalent
% ********** default is to use the global PICKS ***************
%
%
% G.F. Margrave, CREWES, June 2000
%
% NOTE: This SOFTWARE may be used by any individual or corporation for any purpose
% with the exception of re-selling or re-distributing the SOFTWARE.
% By using this software, you are agreeing to the terms detailed in this software's
% Matlab source file.

% BEGIN TERMS OF USE LICENSE
%
% This SOFTWARE is maintained by the CREWES Project at the Department
% of Geology and Geophysics of the University of Calgary, Calgary,
% Alberta, Canada.  The copyright and ownership is jointly held by
% its 'AUTHOR' (identified above) and the CREWES Project.  The CREWES
% project may be contacted via email at:  crewesinfo@crewes.org
%
% The term 'SOFTWARE' refers to the Matlab source code, translations to
% any other computer language, or object code
%
% Terms of use of this SOFTWARE
%
% 1) This SOFTWARE may be used by any individual or corporation for any purpose
%    with the exception of re-selling or re-distributing the SOFTWARE.
%
% 2) The AUTHOR and CREWES must be acknowledged in any resulting publications or
%    presentations
%
% 3) This SOFTWARE is provided "as is" with no warranty of any kind
%    either expressed or implied. CREWES makes no warranties or representation
%    as to its accuracy, completeness, or fitness for any purpose. CREWES
%    is under no obligation to provide support of any kind for this SOFTWARE.
%
% 4) CREWES periodically adds, changes, improves or updates this SOFTWARE without
%    notice. New versions will be made available at www.crewes.org .
%
% 5) Use this SOFTWARE at your own risk.
%
% END TERMS OF USE LICENSE

if(nargin<1)
	error('You must give a figure number')
end
if(nargin<2)
	global PICKS PICKCOLOR
	pts=PICKS;
end

if(isempty(PICKCOLOR))
	clr='r';
else
	clr=PICKCOLOR;
end

[npts,nc]=size(pts);

for k=1:npts-1
	dtdx=(pts(k+1,2)-pts(k,2))/(pts(k+1,1)-pts(k,1));
	x0=.5*(pts(k+1,1)+pts(k,1));
	t0=.5*(pts(k+1,2)+pts(k,2));
	params=[figno .004];
	normraymig(x0,t0,dtdx,params,clr);
end